The invention relates to a grinding roller for the pressure comminution of granular material, in particular for rolling presses for comminuting a bed of material, having a roller shell with wear-resistant surface reinforcement, suitable in particular for autogenous wear protection, and with end-face reinforcement.
In the case of rolling mills, granular, brittle material to be ground is drawn into the roller nip, by which the two rotatably mounted, counter-rotating rollers are separated from each other, and is subjected there to pressure comminution. Also known is so-called material-bed comminution in the roller nip of a high-pressure rolling mill, also known as a rolling press, in which the individual particles of the material to be ground that is drawn into the roller nip by friction are squeezed against one another in a bed of material, i.e. in a charge of material compressed between the two roller surfaces, when a high pressure is applied. The surfaces of the rollers thereby undergo a high level of wearing stress. Therefore, such roller surfaces have to meet at least the following requirements:
They should have high wear resistance, be able to be produced at low cost, be able to be repaired by the operator of the rolling press and also have good drawing-in characteristics for the material to be comminuted.
It is known to make the roller surfaces of rolling presses more resistant to wear by arranging on the roller surface a multiplicity of prefabricated hard metal bodies, such as stud bolts for example, which can be incorporated in corresponding blind-hole bores of the roller shell (EP-B-0 516 952 FIG. 2).
In the case of this so-called grid armoring, the stud bolts protrude outward from the roller surface to such a great height and are arranged at such a distance from one another that, during operation of the rolling press, on the roller surface the interstices between the stud bolts remain filled with the pressed-together fine-grained material, which forms autogenous wear protection for the roller surfaces and, on account of its roughness, also has good drawing-in characteristics. This known roller surface reinforcement with alternating zones of highly wear-resistant material and intermediate spatial zones of other wear resistance has proven to be successful in practice in the material bed comminution of ore material in particular.
However, the end faces of the rollers or the roller shells of rolling presses are also subjected to high levels of wear, in particular when they are used for ore crushing. It is known from DE-C-40 32 615 to reinforce the end faces of the rollers of rolling presses in the region of the peripheral edge of the roller by applying welding material to this region by build-up welding. Apart from the fact that it is questionable whether operators of such machines are capable of building up the wear protection themselves in the case of repair, the wear resistance is limited, because the welding technique cannot be used for applying very hard materials. It has already been attempted to protect the end faces of rolling presses by wear plates in the form of segments of a circle, which are welded at least onto the outer circumference of the roller shell. If these welded-on plates become worn in the course of operating the rolling press, material may be pressed into the radial gap between the end face of the roller and the wear plate and the wear plate forced out of its anchorage, so that the effort involved in maintaining this kind of wear protection for a grinding roller end face is considerable.